Abstract
Abstract: :
Purpose: To determine the cytotoxicity potential of soft contact lens care products and benzalkonium chloride (BAK) with colorimetric in vitro assays using an immortalized human corneal epithelial cell line (HCE-T). These colorimetric assays are useful for the quantitative factor-induced cytotoxicity within a 24 to 96 hour period of cell culture. Methods: Lens care solutions were tested diluted 1:3 with growth medium. BAK was used as a cytotoxic control at 10, 5, 2.5 and 1.25 ppm. Tests used were the cell viability assay using MTS/PES (MTS/PES), and cell membrane integrity assay using neutral red uptake release (NRUR). The endpoint was spectrophotometric measurement using a microplate reader. The data were expressed as the mean optical densities of the test concentrations versus the nontoxic optical densities of the control well. The optical densities were compared using ANOVA/Tukey HSD test for statistical significance. Results: Based on these studies, the following 1:3 diluted lens care solutions were not statistically significant at 48 hours exposure using the MTS/PES and NRUR: SOLOcareTM PLUS, COMPLETE® Comfort PLUSTM and BAK at 1.25 ppm. The following solutions were statistically significant to the control using the MTS/PES and NRUR assays: ReNu MultiPlus®, and Alcon OPTI-FREE® Express® with AldoxTM, BAK 10 , 5 and 2.5 ppm. Conclusions: The use of these two in vitro assays has allowed the evaluation of lens care solutions and BAK cytotoxicity in HCE-T cells through the analysis that only living cells are able to metabolize MTS/PES and uptake neutral red. MTS/PES and NRUR results with HCE-T cells exhibited data which were previously reported 1 with L929 cells evaluating biological reactivity based on the USP Elution Test (least to greatest cytotoxicity potential) was: SOLOCare = COMPLETE Comfort Plus < ReNu << Alcon OPTI-FREE® Express® with Aldox. Future investigations using human corneal conjunctiva cells (ATCC-CCL 20.2) may be performed for comparative in vitro results.
Keywords: contact lens • cornea: epithelium • ocular irritancy/toxicity testing